I'm glad this subject came up! I also was dumb folded now three years ago, not understanding why my seemingly perfectly healthy and thriving Impatiens walleriana almost from one day to the other suddenly looked distressed, yellowing leaves falling off, leaving the stems bare and bending down, falling flowerbuds etc..I didn't know at the time what could have been the cause, they where planted all in different locations and all where affected. The two next years nearly exactly the same scenario happened, in the mean while I had found out about the devastating disease!
Interesting enough, that first year in 2010, I had an Impatiens walleriana grown that came up in a pot of an Elephants Ear I had collected in the wild in the rain forests of Brazil during my trip that time. It must have smuggled itself in as a seed.
In the wild they do grow very tall, mine became nearly 1m tall. This plant got NOT infected, I even overwintered it inside and it did very well, the next season outside it still did well again growing very tall and vigorous. All the others bought, fell victim once more to the dreadful disease. Eventually I lost the Brazilian one, not by the disease, but probably from getting too wet after a very long period of excessive rains in late Autumn, I had waited too long too to take it inside, but I had collected seed and am now growing a couple of seedlings, also from seed I collected from the infected bought plants. I had read somewhere that the seed is not affected by the disease..Again the seedlings from the Brazilian Impatiens are significantly taller. I'll see what will happen this coming season..
